Lord Justice Turner told the jury in the trial, lasting seven weeks at Preston Crown Court, he will complete his summing up on Tuesday morning and the jury will then be sent out to consider its verdicts.

Ms Hartley, who had answered the door to 'bunny boiler' Williams, was left in a pool of blood in the hallway of her £500,000 home, having suffered more than 40 stab wounds, the prosecution alleged.

Her partner, ex-fireman Ian Johnston, 57, away on a skiing trip at the time, was the object of desire for 'jealous and obsessive' Williams who wanted successful businesswoman Ms Hartley out of the way, it is claimed.

Summing up the evidence on Monday, August 15, Lord Justice Turner told the jury: “Both these defendants have denied their guilt on the basis Sarah Williams never did it and Katrina Walsh on the basis she thought she was involved in an elaborate game rather than something which would end in violence.

The jury heard the pair travelled to Germany to buy the stun-gun last December and, exactly a week before Ms Hartley was allegedly murdered, Walsh delivered flowers to her door in a dry run for their plans.

Williams, who was a 'kept woman' supported by her wealthy 'sugar daddy' boyfriend, married David Hardwick, 75, and wanted to be with Mr Johnston after they met at the dry-ski slope Chill Factore in Manchester in 2012.

After a brief relationship broke down, Mr Johnston had begun a new life with Ms Hartley, the two of them setting up home together in Helmshore, Lancashire.

But sex texts and explicit photos continued to be exchanged between Mr Johnston and Williams right up to just days before the murder, the court heard.

Mr Johnston has denied he “led her on”, telling the jury the relationship was “just sex” but Walsh told police Williams would “do anything” to be with Mr Johnston, even planting secret tracker devices on his car to follow his movements.